Michael,
You can't "assign" the Intake and Return valve.. They are preprogrammed.. On the main board you plug your Intake valve into the Intake connection and the Return valve into the Return connection.
The Intake valve is the automated valve in front of the main pump and selects if water is coming from the pool or the spa
The Return valve is the automated valve after the filter that sends water back to either the Pool or the Spa..
Valves A and B can be assigned to a circuit.. As an example, if you have a Circuit called "Waterfall" and assign it to valve A, then when you turn on the waterfall circuit, the
A valve will turn and allow water to flow to the waterfall...
Thanks,
Jim R.